During the manufacture of a display panel (i.e. a liquid crystal display or a TFT-LCD), a layer of photo-spacers (PS) is usually formed between an array substrate 10 and a color filter (CF) substrate 20 for supporting a cell gap between the array substrate 10 and the color filter substrate 20. In the process, it should be ensured that height of the cell gap is equal everywhere.
As shown in FIG. 1A, the photo-spacers are classified into primary photo-spacers 21 and secondary photo-spacers 22. The primary photo-spacer 21 is connected with a thin film transistor (TFT) 11, and an end of the secondary photo-spacer is hung in the air. In this case, there is a height difference between the primary photo-spacer 21 and the secondary photo-spacer 22, i.e. a photo-spacer stage difference 30. In a usual case, only the primary photo-spacer 21 is working. As shown in FIG. 1B, the secondary photo-spacer 22 works only when the panel is squeezed.
In manufacturing a curved television, the theory of which is shown as FIG. 1B, since the curved television has a certain radian to be inward concave or outward convex, a sliding force is generated between the array substrate 10 and the color filter substrate 20. The leftward and rightward sliding forces are respectively generated on the left and right sides of the panel with respect to the center of the panel served as a base point, and a force produced by squeezing the top substrate 10 and the bottom substrate 20 is greater than the forces on the left and right sides. Since the stage differences 30 between the primary photo-spacers and the secondary photo-spacers are designed in an equal manner, i.e. the height difference between the primary photo-spacer 21 and the secondary photo-spacer 22 is equal everywhere, the center portion will be seriously squeezed by stress. Therefore, the cell gap of the center of the curved panel is smaller than both of the sides thereof, so that, the penetration rate and the response time of the center are different from the sides, thereby decreasing the optical performance of the curved liquid crystal panel.
Accordingly, designing a photo spacer suitable for a curved display panel to ensure a uniform thickness and stable quality has become a major direction for research and development of liquid crystal display equipments.